A meteorite exploded over Chelyabinsk, Russia on Friday morning, causing a sonic boom and injuring more than 900 people. Russia’s space agency Roscosmos said the giant fireball that sped across the sky was traveling 19 miles per second before it exploded, causing a bright light that could be seen 125 miles away in Yekaterinburg. Most injuries occurred as a result of flying glass from shattered windows and at least 100 people remain in hospital, Reuters reports.

When the meteorite exploded over the industrial city 90 miles of Moscow, it caused a sonic boom, according to the Interior Ministry. Such occurrences are rare, according to officials working with the emergency ministry, but one official said the explosion “might have been linked to an asteroid the size of an Olympic swimming pool due to pass Earth at a distance of 27,520 km (17,100 miles),” but Reuters reports that this has not been confirmed.

The Emergencies Ministry called the morning event a “meteor shower in the form of fireballs” but urged residents not to panic. Meanwhile, Chelyabinsk city authorities are asking people to stay home unless they have to collect their children, according to Reuters, whose correspondent was on the scene. NASA said that the 2012 DA14 asteroid, which is roughly 46 meters in diameter, would get closer to earth than any prior since the agency began observing them. A search term is looking for the meteorite’s debris.